A photoinduced electron-transfer strategy for switchable fluorescence and phosphorescence in lanthanide-based coordination polymers

Abstract

Smart optical materials with tunable fluorescence and room temperature phosphorescence (RTP) exhibit promising application prospects in the field of intelligent switches, information security, etc. Herein, a tetraimidazole derivative was grafted to one-dimensional lanthanum-diphosphonate through H-bonds, generating a coordination polymer (CP), (H₄-TIBP)·[La₂Li(H₂-HEDP)₄(H-HEDP)]·3H₂O (termed La; TIBP = 3,3,5,5-tetra(imidazole-1-yl)-1,1-biphenyl; H₄-HEDP = 1-hydroxyethylidene-1,1-diphosphonic acid) with a three-dimensional supramolecular structure. La shows dynamic fluorescence from blue to red and switchable monotonous yellowish-green RTP, which can be manipulated by reversible photochromism. It is worth noting that Eu³⁺/Tb³⁺-doped CPs exhibit time-resolved (red to yellow) and monotonous green afterglow, respectively, which can be attributed to multiple emissions with different decay rates. The dynamic and multicolor luminescence endows these CPs with potential for application in the domains of optical communications, multi-step encryption, and anti-counterfeiting. This work not only integrates color-adjustable fluorescence, switchable RTP, and photochromism in one material, but also realizes the manipulation of the resultant optical performances via photochromism, paving the pathway for the design and synthesis of smart optical materials.